db.command.aggregate.min
1. Operator Description
Function: Returns the minimum value in a set of numbers.
Declaration: db.command.aggregate.min(<expression>)
2. Operator Parameters
Field | Type | Required | Description |
---|---|---|---|
- | Expression | Required | An expression is a string in the form of $ + specified field . |
3. Sample Code
Suppose the collection students
contains the following records:
{ "group": "a", "name": "stu1", "score": 84 }
{ "group": "a", "name": "stu2", "score": 96 }
{ "group": "b", "name": "stu3", "score": 80 }
{ "group": "b", "name": "stu4", "score": 100 }
Using min
, you can calculate the lowest score in different groups (group
). The code is as follows:
// Sample code in the Cloud Function environment
const tcb = require('@cloudbase/node-sdk')
const app = tcb.init({
env: 'xxx'
})
const db = app.database()
const $ = db.command.aggregate
const _ = db.command
exports.main = async (event, context) => {
const res = await db
.collection('students')
.aggregate()
.group({
_id: '$group',
minScore: $.min('$score')
})
.end()
console.log(res.data)
}
The returned data result is as follows:
{ "_id": "b", "minScore": 80 }
{ "_id": "a", "minScore": 84 }